Shaft Seals, Replace?

[Golfman25]

So long story made short. Boat is a 1998 370 Sundancer with 7.4s and V-drives. It originally came with the Tides lip seals. At some point, a previous owner replaced the Tides with the PSS face seals. Pure speculation on my part, but probably done prior to 2016. So the bellows, while it looks good (no cracks) is most likely past its 6 year replacement recommendation. So fast forward to today.

They are fine at rest, and at idle RPMs -- no leaks. I do get some leaking at cruise, say 3000 RPMs (haven't really dialed in when the leaking begins). Bilge pumps may come on every 30+ min or so. The port bellows looks really compressed, probably 1/2 to 1 inch more than what is stated in the installation manual. Haven't measured the starboard.

Talked to the marina, and they are now using the Lasdrop mechanical seals. https://lasdrop.com/index.php/gen2/
The primary difference is that they don't use the bellows to provide the face seal pressure, but instead use a spring and put it on the rotating half of the seal.

So here are my options. (1) Fart around with it and try to get more compression to get a few more years out of them. (2) Do a bellows replacement (saving the marginal seal cost) or (3) go with the marina and the new lasdrop seals? What say you? Thanks in advance.

 

[dtfeld]

Would this be done as a planned or unplanned haul out? If it is a minor leak and you can get to the end of the season, either leave it be or redo the tension on the seals and try to run out the clock.

Then over the winter, you can make a better decision on which seal best suits your needs> But regardless, you are pulling the boat and shafts, so what else needs attention while your digging in that deep? At least new cutless bearings, (they are cheap), and maybe check/scan the props and shafts.

The mechanical seals look interesting, but I don't know much about them. Is there a big $$$ or warranty difference? I think at the end of the day they all have pros/cons and a definite life span.

 

[Golfman25]

Yeah, winter project (sux, it's right around the corner up here). And would do cutless bearings and alignment (in spring) as well. I am mostly a "trawler" speed boater with the admiral and dog, so I could probably "milk" it for a few years.

As for the different seal types. The issue with the tides lip seals is they contact the shaft. Thus they can wear a groove in the shaft, which you can kind of see, feel on mine. That's why my marina went to the PSS seal. PSS is a mechanical face seal. The problem is the bellows -- that's the weak point (just like on the outdrives we talk about on here), and if they fail, look out below. I am not really a fan of using a bellows for double duty -- applying pressure and keeping water out (they have actually introduced a "pro" version to address some of the weaknesses). I like the lasdrop as they flipped the seal around and use a spring to apply the pressure. Cost isn't much more and there is no bellows replacement schedule. So you're basically done, unless your spring goes and in fresh water, that's not much of a concern for me.

 

[dtfeld]

Keep me posted. I went back with Tides (one when I bought the boat in early 2018 and another last year) and my shafts have multiple grooves. I'd image I'll get several years, but next time I either need to have the shafts resurfaced/replaced or go to a pressure plate style. But interesting concept.

 

[dtfeld]

Oh.., and you go first with the new seal style!!

 

[Golfman25]

Oh.., and you go first with the new seal style!!

Actually, the mechanical face seal has been around for 50+ years (if not longer). We make components for one of the largest seal companies and we have prints from the 50s and 60s.

 

[ttmott]

I've had to change a seal in the water, in the middle of nowhere. On a Sundancer no less. But, I was able to do it with the Tides arrangement (I think Lasdrop also have a replaceable lip seal system) - can that be done with a mechanical face seal?
Something to consider.

 

[Maybe A Dancer]

When I did the 2005 refit to Yanmar diesels in my 10 Meter Trojan International, I upgraded to the 1.75" PSS/PYI shaft seals.

Had to do a couple of adjustments, and "cleanouts"

On that inline transmission boat - not easy to access.

I then "forgot" about them, truly.

In 2020 I came across a thread on the Trojan forum about replacing the bellows - and I suddenly REMEMBERED that I had them.

Boat was kept on a lift behind the house. Was a relatively easy process to replace them myself.

At time of purchase the 450 DA had 1.75" PSS/PYI on it with receipts showing a 3 year old install.

They leaked intermittently and I attempted readjustment and face cleaning to no avail.

Found the likely cause of failure to be a weak water supply, caused by a crusted up salt water cooling system in the risers/elbows/tubes on my 26 year old, 435 hour, floating bar, dock queen.

Once that was restored to baseline and the shaft seals replaced with new, no further issues.

NOTE:

I added crossover system for the salt water cooling side, with a little different approach.

I included ball valves (tie wrapped open), above the TEE.

The purpose of which would be to eliminate any possibility of saltwater backing up into the disabled engine.

The benefit of having the saltwater lines tied together is reducing the possibility of starving one side of cooling/pressure water required for operation.

Conclusion:

• In my ignorance with the Trojan, the actual bellows lasted for 15 years - DON'T TRY THIS AT HOME
• The likely cause of premature failure on the 450DA was the lack of adequate salt water cooling flow.
• Make sure your flow is good, as this is at the END of the line for the raw water system.
• The addition of the crossover is a bit of insurance.

My own plan is to maintain the cooling system to baseline and replace the bellows & carbon surface during a scheduled bottom paint haulout.

BEST !

RWS

 

[Golfman25]

I've had to change a seal in the water, in the middle of nowhere. On a Sundancer no less. But, I was able to do it with the Tides arrangement (I think Lasdrop also have a replaceable lip seal system) - can that be done with a mechanical face seal?
Something to consider.

The fix on the face seal is to compress the bellows, which can be done in the water.

 

[ttmott]

The fix on the face seal is to compress the bellows, which can be done in the water.

What happened to me is some monofilament line wrapped up the prop shaft and got into the seal and took it out.
Years ago when we replaced the seal system on my 400DA my mechanic wanted to stay away from the mechanical style. His reasoning was that where we run our boats there is a lot of grit and turbidity suspended in the water and that grit is not friendly to the mechanical style. So based upon that I've stayed with the lip style.

 

[Golfman25]

Bumping back to the top as it's decision time. In working with the PSS people, it's probably time to change out the PSS seal bellows even though the look good. I could probably get by another year if I moved the seal faces down to obtain more compression, but I am within the max compression range as it is. To replace the seals marina is asking for $6k-7,000. What are we doing?

 

[Maybe A Dancer]

WOW !

That seems a bit, no seems really high for the amount of work involved.

As stated above, I did my former boat (1.75" shafts) with a helper, on the lift behind my house.

Far easier to pull those shafts back while on land !

Maybe the problem is simply Bidenomics?

Also, whenever I'd get a drip or leak a quick cleaning of the surfaces always took care of the problem.

*** PSS/PYI offers a locking collar, to insure nothing slips on the shaft. Great insurance!

If you want to be extra anal (like me) take a sharpie marker and mark the shaft on both sides. That way you will easily see if something has slipped forward.

BEST !

RWS

 

[Skybolt]

Bumping back to the top as it's decision time. In working with the PSS people, it's probably time to change out the PSS seal bellows even though the look good. I could probably get by another year if I moved the seal faces down to obtain more compression, but I am within the max compression range as it is. To replace the seals marina is asking for $6k-7,000. What are we doing?

It sounds like you need another marina. That price is, well, absurd at best.

It sounds like you could do this yourself? At those prices, I would certainly be doing it myself.

 

[dtfeld]

Bumping back to the top as it's decision time. In working with the PSS people, it's probably time to change out the PSS seal bellows even though the look good. I could probably get by another year if I moved the seal faces down to obtain more compression, but I am within the max compression range as it is. To replace the seals marina is asking for $6k-7,000. What are we doing?

Damn. Are they gold plated? Seals should be $500 ea. Maybe 4 hours a side and a round trip haul out. Even in the current market, $3500-$4500?

I don’t think anything wrong with either, but going back with a face seal after having the Tides is my next move.

 

[Skybolt]

I am not going to post how long I have had these but I have PSS and think they are great. I get short hauled every year and during the bottom painting and waxing, I clean them up. Then back in.

 

[Golfman25]

It sounds like you need another marina. That price is, well, absurd at best.

It sounds like you could do this yourself? At those prices, I would certainly be doing it myself.

The charge like lawyers around here — up to $200/hr these days. So looking at about 12 man hours per side. Probably a 2 man job - one inside upside down and one outside working the shaft. So I don‘t know. But yeah not cheap.

 

[Skybolt]

The charge like lawyers around here — up to $200/hr these days. So looking at about 12 man hours per side. Probably a 2 man job - one inside upside down and one outside working the shaft. So I don‘t know. But yeah not cheap.

Can't be 12 hrs a side. I venture to say it's not 12hrs for both sides. I did mine in ~6hrs. That was removing the old style shaft log and cleaning the shaft with emery cloth and that was both sides. Granted the collar can be tough to get off, so call it 8hrs for both sides. And that was without help and I work very slow.

 

[Maybe A Dancer]

heating the collar can be a great time saver....

BEST !

RWS

 

[Golfman25]

Can't be 12 hrs a side. I venture to say it's not 12hrs for both sides. I did mine in ~6hrs. That was removing the old style shaft log and cleaning the shaft with emery cloth and that was both sides. Granted the collar can be tough to get off, so call it 8hrs for both sides. And that was without help and I work very slow.

straight drives? Yeah, they would be much easier than my V-drives. These fkg things are under the engine. I can barely get down there to look at them, let alone remove and replace. It would take me days.

I agree it's expensive and the hours probably padded. Unfortunately, not much competition around here, so pricing is high.

Eventually it will have to be done. Just trying to decide if now is the time or I try to squeeze them down and get a year or two out of them. The bellows thing has me "worried." I do think their 6 year replacement is a little soon to "cover our a$$." Decisions, Decisions.

 

[Maybe A Dancer]

Can't comment on the 370.

Had plenty of access on the 10 meter (straight drives) as well as on the 450DA (V-Drives)

I do understand the additional time/labor cost for the tight spaces, however the number seems high to me.

But I'm not a marina operator.....

BEST !

RWS